_form.html.erb

<%= form_for (@gallery, :html => {:multipart => true}) do |f| %>
  <% if @gallery.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@gallery.errors.count, "error") %> prohibited this gallery from being saved:</h2>

      <ul>
      <% @gallery.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>

<%= f.fields_for :gallery_photos do |gf_form| %>
     <%= gf_form.label :photo, 'Photo:' %>
     <%= gf_form.file_field :photo %>
<% end %>

  <div class="actions">
    <%= f.submit %>
  </div>

<% end %>

galleries_controller.rb

class GalleriesController < ApplicationController
  # GET /galleries
  # GET /galleries.xml
  layout "admin"
  def index
    @galleries = Gallery.all

    respond_to do |format|
      format.html # index.html.erb
      format.xml  { render :xml => @galleries }
    end
  end

  # GET /galleries/1
  # GET /galleries/1.xml
  def show
    @gallery = Gallery.find(params[:id])
    @gallery_photo = @gallery.gallery_photos.find(params[:all])




    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @gallery }
    end
  end

  # GET /galleries/new
  # GET /galleries/new.xml
  def new
    @gallery = Gallery.new
    @gallery_photos = @gallery.gallery_photos.build


    

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @gallery }
    end
  end

  # GET /galleries/1/edit
  def edit
    @gallery = Gallery.find(params[:id])
  end

  # POST /galleries
  # POST /galleries.xml
  def create
    @gallery = Gallery.new(params[:gallery])
   
    gallery_photo = GalleryPhoto.new

    gallery_photo = GalleryPhoto.find(:all, :conditions => {:gallery_id => @gallery.id})


    respond_to do |format|
      if @gallery.save
        format.html { redirect_to(@gallery, :notice => 'Gallery was successfully created.') }
        format.xml  { render :xml => @gallery, :status => :created, :location => @gallery }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @gallery.errors, :status => :unprocessable_entity }
      end
    end
  end

  # PUT /galleries/1
  # PUT /galleries/1.xml
  def update
    @gallery = Gallery.find(params[:id])

    respond_to do |format|
      if @gallery.update_attributes(params[:gallery])
        format.html { redirect_to(@gallery, :notice => 'Gallery was successfully updated.') }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @gallery.errors, :status => :unprocessable_entity }
      end
    end
  end

  # DELETE /galleries/1
  # DELETE /galleries/1.xml
  def destroy
    @gallery = Gallery.find(params[:id])
    @gallery.destroy

    respond_to do |format|
      format.html { redirect_to(galleries_url) }
      format.xml  { head :ok }
    end
  end
end

show.html.ebr

<p id="notice"><%= notice %></p>

<p>
  <b>Name:</b>
  <%= @gallery.name %>
</p>

<%= image_tag @gallery_photo.photo.url(:medium) %>



<%= link_to 'Edit', edit_gallery_path(@gallery) %> |
<%= link_to 'Back', galleries_path %>